Drag and drop menulet
This subject came up last week and I spend a little time googling (and looking at Apple's sample code) without finding a simple answer. I did find the following tutorial:
http://cocoadevcentral.com/articles/000056.php
The tutorial is rather old, however I'm fairly sure you'll get it to work. My experience with Cocoa is that the techniques used by most Cocoa frameworks are not obvious - however they are ingeneous. So it might take a bit of effort to get it to work, however when you do, you will be very pleased and say "Ah, yes of course - how elegant".
When you find the answer - perhaps you could share it with the rest of us - and possibly reply to this: http://www.cocoaforum.com/2010/06/24/creating-drag-drop-zone-from-files-in-nsview/#post0
On the other hand, if you're stuck, please let me know and I'll try again after work this evening to investigate this.